Optical recording medium, optical pickup apparatus, and recording and reproducing apparatus

Abstract

The invention provides: an optical recording medium having the changeability and compatibility of media and a large capacity in three dimensions; an optical pickup apparatus for the same and a control apparatus for the same. The present invention is an optical recording medium comprising a superposition of: a control layer provided with a tracking control signal formed in advance; and a photosensitive material having a variable optical property; wherein regions provided with a distribution of discrete portions each having an optical property changed correspondingly to data to be recorded within the volume of said photosensitive material are superposed in layered structure on a path along which a light beam guided on the basis of said tracking control signal in said control layer goes.

What is claimed is:  
     
         1 . An optical recording medium comprising a superposition of: a control layer provided with a tracking control signal formed in advance; and a photosensitive material having a variable optical property; wherein regions (each referred to as a “recording track”, hereafter) provided with a distribution of discrete portions each having an optical property changed correspondingly to data to be recorded within the volume of said photosensitive material are superposed in layered structure(each layer is referred to as a “recording layer”, hereafter) on a path (referred to as a “control track”, hereafter) along which a light beam guided on the basis of said tracking control signal in said control layer goes.  
     
     
         2 . An optical recording medium according to  claim 1 , wherein said photosensitive material has prominent nonlinearity with respect to light intensity.  
     
     
         3 . An optical recording medium according to  claim 1 , wherein position information is recorded in said control layer.  
     
     
         4 . An optical recording medium according to  claim 1 , wherein a signal for identifying a layer is recorded in each layer.  
     
     
         5 . An optical recording medium according to  claim 4 , wherein said signal for identifying a layer is recorded at a position having a predetermined relation to the recording position of a signal formed in said control layer.  
     
     
         6 . An optical recording medium according to  claim 4 , wherein: said position information is recorded in said control layer in a discrete manner; and a recording layer identification signal is recorded in a region of each recording layer superposed on the region in which said position information is recorded.  
     
     
         7 . An optical recording medium according to  claim 1 , wherein each recording layer is irradiated with light through said control layer, whereby a signal is recorded or reproduced.  
     
     
         8 . An optical recording medium according to  claim 1 , wherein on the recording tracks of all said recording layers superposed on said control track in a predetermined region, the optical property of said photosensitive material is changed entirely.  
     
     
         9 . An optical recording medium according to  claim 1 , wherein non-rewritable intrinsic information is recorded on said control track.  
     
     
         10 . An optical recording medium according to  claim 1 , wherein a pair of wobble signals are recorded at positions which are different in the longitudinal directions of said recording track of each recording layer and which are displaced oppositely in the thickness directions of said recording layer.  
     
     
         11 . An optical recording medium according to  claim 10 , wherein said pair of wobble signals are recorded at positions having a predetermined relation to the recording position of a signal formed in said control layer.  
     
     
         12 . An optical recording medium according to  claim 1 , wherein: a pair of wobble signals are recorded at positions which are different in the longitudinal directions of said recording track of each recording layer and which are displaced oppositely in the thickness directions of said recording layer; and another pair of wobble signals are recorded at positions which are different in the longitudinal directions of said recording track of each recording layer and which are displaced in the left and right directions.  
     
     
         13 . An optical recording medium according to  claim 1 , comprising a clamp section for clamping the optical recording medium onto a control apparatus, wherein said clamp section is formed with material having a hardness higher than that of said photosensitive material.  
     
     
         14 . An optical recording medium according to  claim 1 , wherein the front and back surfaces of the optical recording medium are covered with material having a hardness higher than that of said photosensitive material.  
     
     
         15 . An optical pickup apparatus which focuses images simultaneously at a first imaging point and a second imaging point which are two different points on the same optical axis, wherein: focus control and tracking control are carried out on the basis of light returned from said first imaging point; and recording or reproduction is carried out by light focused on said second imaging point.  
     
     
         16 . An optical pickup apparatus according to  claim 15 , which is used for an optical recording medium comprising a superposition of: a control layer provided with a tracking control signal formed in advance; and a photosensitive material having a variable optical property; wherein: 
 focus control and tracking control are carried out on the basis of light from said first imaging point positioned in the control layer; and recording or reproduction is carried out by light focused on said second imaging point positioned within the photosensitive material.    
     
     
         17 . An optical pickup apparatus which focuses images simultaneously at a first imaging point and a second imaging point which are two different points on the same optical axis, said optical pickup apparatus comprising 
 a first focus adjustment section and a second focus adjustment section, wherein: 
 when said first focus adjustment section is adjusted, said two imaging points move; and  
 when said second focus adjustment section is adjusted, said second imaging point moves solely.  
   
     
     
         18 . An optical pickup apparatus according to  claim 17 , comprising at least a laser and a coupling lens, wherein: light outputted from said laser goes through said coupling lens and thereby is focused on said second imaging point; and said second focus adjustment section adjusts the distance between said laser and said coupling lens in the optical path directions and thereby adjusts the position of said second imaging point.  
     
     
         19 . An optical pickup apparatus according to  claim 17 , comprising at least a collimator comprising a plurality of lenses, wherein: light outputted from a laser goes through said collimator and thereby is focused on said second imaging point; and said second focus adjustment section adjusts the distance between said lenses of said collimator in the optical path directions and thereby adjusts the position of said second imaging point.  
     
     
         20 . An optical pickup apparatus used for an optical recording medium comprising a superposition of: a control layer provided with a tracking control signal formed in advance; and a photosensitive material having a variable optical property; said optical pickup apparatus comprising 
 a first laser having a first wavelength and a second laser having a second wavelength shorter than that of said first wavelength, wherein: 
 said first laser reproduces said tracking control signal from said control layer; and  
 said second laser focuses an image in said photosensitive material and thereby records or reproduces a signal.  
   
     
     
         21 . An optical pickup apparatus used for an optical recording medium comprising a superposition of: a control layer provided with a tracking control signal formed in advance; and a photosensitive material having a variable optical property; said optical pickup apparatus comprising 
 a first laser, a second laser, a third laser and a fourth laser, wherein: 
 said first laser reproduces the tracking control signal from the control track provided in said control layer;  
 said second laser records at least a signal selected from the group consisting of a clock signal, a position information signal, a recording layer identification signal and a data signal, onto the recording track of each recording layer;  
 said third laser records a first wobble signal at a position displaced from said recording track of each recording layer into a thickness direction of the recording layer; and  
 said fourth laser records a second wobble signal at a position displaced from said recording track of each recording layer into the direction opposite to said first wobble signal.  
   
     
     
         22 . An optical pickup apparatus comprising a second laser, a third laser and a fourth laser, wherein: 
 said second laser records at least a signal selected from the group consisting of a clock signal, a position information signal, a recording layer identification signal and a data signal, into each recording layer, and at the same time, reproduces a tracking control signal from said control layer;    said third laser records a first wobble signal at a position displaced from said recording track of each recording layer into a thickness direction of said recording layer; and    said fourth laser records a second wobble signal at a position displaced in the direction opposite to said first wobble signal.    
     
     
         23 . An optical pickup apparatus according to  claim 21  or  22  further comprising a fifth laser and a sixth laser, wherein: 
 said fifth laser records a third wobble signal at a position displaced from the longitudinal directions of said recording track in each recording layer into either left or right direction; and  
 said sixth laser records a fourth wobble signal at a position displaced in the direction opposite to said third wobble signal.  
 
     
     
         24 . An optical pickup apparatus which carries out focus control on the basis of reproduced signals from said pair of wobble signals recorded on an optical recording medium according to  claim 10 .  
     
     
         25 . An optical pickup apparatus which carries out focus control on the basis of reproduced signals of said pair of wobble signals recorded on an optical recording medium according to  claim 10  or  11 , and which carries out tracking control on the basis of the tracking control signal formed in said control layer.  
     
     
         26 . An optical pickup apparatus which carries out focus control on the basis of said pair of wobble signals recorded at positions displaced in the directions opposite to each other in the thickness directions of said recording layer of an optical recording medium according to claim  12 ; and which 
 carries out tracking control on the basis of said another pair of wobble signals recorded at positions displaced from said recording track within said recording layer into the left and right directions.    
     
     
         27 . A control apparatus for an optical recording medium, comprising an optical pickup apparatus according to  claim 15  or  17 , wherein the distance between said two imaging points is changed discretely in equal spacing in the optical axis directions, whereby recording or reproduction of a signal is carried out.  
     
     
         28 . A control apparatus for an optical recording medium, comprising an optical pickup apparatus according to  claim 15  or  17 , wherein said first imaging point is changed continuously in the optical axis directions, whereby focus control is carried out, and wherein the distance between said two imaging points is changed discretely in equal spacing in the optical axis directions, whereby recording or reproduction of a signal is carried out.  
     
     
         29 . A control apparatus for an optical recording medium, comprising an optical pickup apparatus according to  claim 15  or  17 , wherein the light focused on said second imaging point is adjusted using a focus error signal obtained from the returned light of said light, so that said light is focused on a point identical to said first imaging point, and after that, said second imaging point is shifted discretely in equal spacing, whereby recording or reproduction of a signal is carried out.  
     
     
         30 . A control apparatus for an optical recording medium according to  claim 8 , wherein: in said predetermined region, the focal position of a light beam is changed from said control layer to each recording layer; the position of said recording track of each recording layer relative to the position of said control layer is stored; and the focal position of said light beam is set on the basis of the stored position information of each recording track, whereby recording or reproduction is carried out.  
     
     
         31 . A control apparatus for an optical recording medium comprising a superposition of: a control layer provided with a tracking control signal formed in advance; and a photosensitive material having a variable optical property; said control apparatus comprising 
 an optical pickup apparatus according to claim  17 ; wherein: 
 said first focus adjustment section positions said first imaging point into said control layer, whereby focus control and tracking control are carried out on the basis of the reflected light of the light focused on said first imaging point; and  
 said second focus adjustment section moves said second imaging point discretely in equal spacing in the directions of the optical axis relatively to said first imaging point, whereby a signal is recorded into or reproduced from said photosensitive material.  
   
     
     
         32 . A control apparatus for an optical recording medium according to  claim 31 , wherein said first focus adjustment section moves said first imaging point continuously in the directions of the optical axis, whereby focus control is carried out.  
     
     
         33 . A control apparatus for an optical recording medium according to  claim 31 , wherein: 
 position information is further recorded in said control layer; and    it is determined whether a recording layer identification signal is recorded in the photosensitive material superposed on the region in which said position information is recorded, whereby in case that no recording layer identification signal is recorded, a recording layer identification signal is newly recorded.    
     
     
         34 . A control apparatus for an optical recording medium according to  claim 31 , wherein no signal can be newly recorded in said photosensitive material in a predetermined region in which at least a signal selected from the group consisting of a recording layer identification signal, a wobble signal and a position information signal has been recorded.  
     
     
         35 . A control apparatus for an optical recording medium in which recording tracks are formed in layered structure within the volume of a photosensitive material, wherein: 
 said control apparatus comprises an optical pickup apparatus which focuses images simultaneously at a first imaging point and a second imaging point which are two different points on the same optical axis; and    each of said first and second imaging points is positioned onto the recording track of a different layer to each other, whereby recording or reproduction is carried out on each recording track.    
     
     
         36 . A control apparatus for an optical recording medium according to  claim 35 , wherein: 
 said optical pickup apparatus comprises a first laser and a second laser, whereby a light beam outputted from said first laser is focused on said first imaging point, while a light beam outputted from said second laser is focused on said second imaging point; and    said first light beam records a signal onto a recording track, while said second light beam reproduces a signal from another recording track.